Cooling means for an air conditioning system

ABSTRACT

A PLURALITY OF FINNED COOLING COIL UNITS ARE ARRANGED IN A VERTICAL SERIES IN AN AIR CONDITIONING SYSTEM WITH THE COOLING COIL UNITS INCLINED FOR COMPACTNESS, TO ACCOMMODATE A HIGH AIR FLOW VELOCITY AND, FOR EFFECTIVE DISCHARGE OF CONDENSATION. A DRIP PAN IS DISPOSED UNDER EACH COOLING COIL UNIT AND SERVES AS A MOVABLE BAFFLE TO PROVIDE SELECTIVE BYPASSING OF THE UNITS, AND WHEN DESIRED, TO   COVER THE UNITS TO PREVENT AIR FLOW THERETHROUGH, FOR WHICH PURPOSE THE DRIP PANS INCLUDE A LAYER OF HEAT INSULATING MATERIAL THAT PREVENTS SUBSTANTIAL HEAT TRANSFER BETWEEN THE CIRCULATING AIR AND THE COVERED UNITS.

Jan. 19, 1971 3,555,847

COOLING MEANS FOR AN AIR CONDITIONING SYSTEM Filed March 28, 1969 J.- T. MocARTr-:R

2. Sheets-Sheet 1 INVENTOR. JAMES T. McCARTER w, 1.9m 1.1-.MCCARTER 3555,84?

COOLING MEANS FOR AN AIR CONDTIONING SYSTEM Filed March 28, 1969 2 Sheets-Sheet 2 INVENIOR.

BY :mamas 1A /MQCARTE IDM il. S

ATTO NEWS United States Patent O 3,555,847 COOLING MEANS FOR AN AIR CONDITIONING t SYSTEM .Iam'es T. McCarter, 228 McSwain Drive, Greenville, S.C. 29607 Filed Mar. 28, 1969, Ser. No. 811,326 Int. Cl. F25d 21/14 U.S. Cl. 62-286 17 Claims ABSTRACT F THE DISCLOSURE A plurality of finned cooling coil units are arranged in a vertical series in an air conditioning system with the cooling coil units inclined for compactness, to accommodate a high air fiow velocity and, for effective discharge of condensation. A drip pan is disposed under each cooling coil unit and serves as a movable bafiie to provide selective bypassing of the units and, when desired, to cover the units to prevent air flow therethrough, for which purpose the drip pans include a layer of heat insulating material that prevents substantial heat transfer between the circulating air and the covered units.

BACKGROUND OF THE INVENTION The present invention is directed to means in an air conditioning system for cooling circulated air using a vertical series of finned cooling coil units that are inclined to provide compactness, high air flow capacity, and effective discharge of condensation, combined, in the preferred embodiment, with drip pans that serve as baffles and are movable for selective bypass control of the air fiow.

Finned cooling coil units are conventionally used in various types of air conditioning systems to cool circulated air and in some installations the cooling coil units are inclined to suit the particular direction of air flow through the system and the configuration of the structure. For example, in air conditioning systems in which the air flow is in a vertical direction the cooling coil units may be inclined so that the moisture condensing of the units will run down the face of the units and drip into pans disposed under the lower ends thereof. In such arrangements, the inclination of the units from a vertical disposition is limited to avoid dripping except at the lower ends so that narrow drip pans can be used without significantly restricting the air flow passage. Examples of such arrangements are disclosed in Hopkinson U.S. Patent No. 2,959,031 and Herbert U.S. Patent No. 3,212,- 288. In systems in which the air fiow is in a generally horizontal direction, however, cooling coil units are usually simply disposed in a vertical disposition across the air fiow path.

In the more sophisticated conventional air conditioning systems, such as those used to condition air in industrial plants and other large buildings, the cooling coil units are often combined with a bypass arrangement that permits a controlled portion of the air fiow to bypass the cooling coil unit for regulation of the sensible cooling and dehumidification produced by the system. Such conventional bypass arrangements normally require additional structure as well as an enlarged cross-sectional area of the enclosure of the system, resulting in a significant increase in cost and size.

In the air conditioning system of the present invention cooling coil units are uniquely arranged at an inclination that provides for optimum discharge of condensing moisture therefrom While presenting an increased effective surface area in relation to the cross-sectional area of the system so that a compact, high capacity system can be designed. The compactness of the system, as well as its simplicity of construction, are further enhanced 3,555,847 Patented Jan. 19, 1971 lCe by arranging the inclined cooling coil units with bypass spacings therebetween without increasing the overall cross-sectional area and by using drip pans disposed below each unit as bafiies to control the bypass function.

SUMMARY OF THE INVENTION Briefly described, the present invention provides means for cooling circulating air in an air conditioning system that has an air plenum chamber in which air is conditioned as it is circulated therethrough in a predetermined direction. This air cooling means includes a finned cooling coil unit located in the air plenum chamber in the path of the circulated air for passage of the air therethrough to effect cooling thereof. The unit is inclined from a horizontal disposition with its lower end spaced downstream from its upper end, theinclination being sufficient to cause moisture condensing from the cooling air onto the cooling coil unit to begin gravitating along the upstream face thereof sufficiently to form into drops and being sufficiently displaced from a vertical disposition to cause the drops to drip from the; upstream face before reaching the lower end thereof, thereby effecting optimum discharge of condensed moisture while presenting a large effective surface area in relation to the cross-sectional area of the plenum chamber so as to accommodate relatively high air flow velocities that permit a compact structural design of the system.

Combined with the inclined cooling coil unit is a drip pan disposed immediately below the aforementioned lower end of the cooling coil unit to prevent substantial air flow therebetween and extending under the aforementioned upstream face of the cooling coil unit for collection of the condensate dripping from the unit. This location and extent of the drip pan allow unique dual functioning as a drip pan and as a baffle, for which latter functioning the drip pan may be movably mounted.

In the preferred embodiment of the present invention a .generally vertically disposed series of finned cooling coil units is located across the air plenum chamber for cooling of air circulating therethrough in a generally horizontal direction. Each of these cooling coil units is inclined as aforementioned with the lower end of the upper of adjacent units being spaced downstream from the upper end of the adjacent lower unit so as to provide a bypass passage therebetween, which bypass passage is defined by the units themselves and is located within the cross-sectional area occupied by the units for simplicity and compactness.

The inclination of the cooling coil units is in the general range of 25 to 60 from a horizontal disposition, With optimum results being obtained in a usual commercial installation at an inclination of approximately 28 to 30. Condensing moisture is collected as it drips from the cooling coil units by drip pans disposed under the upstream faces of the units, with the drip pans between adjacent cooling coil units extending between the lower end of the upper of adjacent units and the upper end of the lower of the adjacent units to provide -a baffle across the aforementioned bypass passage to restrict air flow therethrough. These drip pans are pivoted adjacent the lower end of the upper of the adjacent units and means are provided for selectively pivoting the drip pans to vary the portion of air bypassing the cooling coil units and thereby regulate the sensible cooling and dehumidification produced by the system. If desired, the drip pans can be pivoted into covering relation across the upstream faces of the units thereabove to cause substantially all of the circulated air to bypass the cooling coil units and thereby render the units inoperative, for which purpose the drip pans may include a layer of heat insulating material that prevents substantial heat transfer between the circulated air and the covered units so that freezing of water in the inoperative cooling coil units will not occur during cold weather operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of an air conditioning system in which the preferred embodiment of the present invention is incorporated, with the top of the housing removed;

FIG. 2 is a Vertical sectional view of the air conditioning system of FIG. 1, taken along line 2-2 of FIG. 1;

FIG. 3 is an enlarged vertical sectional view of the air cooling section of the air conditioning system of FIGS. l and 2, taken along line 3--3 of FIG. 2;

FIG. 4 is an enlarged elevation view of a portion of the air cooling section of the air conditioning system of the preceding figures.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment of the cooling means of the present invention is shown in the accompanying drawings incorporated in an air conditioning system of the large capacity type used in industrial plants and other large buildings, and wherein the air conditioning components are contained in an elongated housing that is mounted exteriorly of the building, as on the roof thereof.

The housing 10 defines therein an air plenum chamber in which air is conditioned as it is circulated therethrough in a generally horizontal direction, as indicated by the air iiow arrows in the figure. As the air flows through the housing 10 it passes progressively through a return air intake section A, an air filtering section B, an outside air intake section C, an air cooling section D, an air heating section E and a discharge section F.

In the return air intake section A return air is received from the conditioned space within the building through suitable ductwork communicating with a return air port 12 formed in the bottom of the housing 10. As the return air enters the housing 10, a portion thereof may, if outside air is subsequently to be added to the recirculating air, be relieved to the atmosphere through relief dampers 14 and louvers 16 formed in the end of the housing 10. These relief dampers are controlled by conventional means to relieve any selected portion of the return air from none to substantially all.

The unrelieved portion of the return air is circulated from the return air intake section A to the air filtering section B where the air is cleaned by passing through a bank of filters 18 of any suitable conventional type, which filters 18 are disposed fully across the air plenum chamber for filtering of all of the air circulated through the section.

As the circulated air leaves the bank of filters 18 it passes through a vertical series of regulating dampers 20 in the outside air intake section C, which section also includes outside air intake dampers 22 formed in the sides and bottom of the housing 10 and through which outside air is drawn into the air plenum and mixed with the recirculated portion of the return air to constitute the air mass ultimately discharged into the space to be air conditioned. The regulating dampers 20 and the outside air intake dampers 22 are controlled by conventional means and are manipulated in relation to the manipulation of the aforementioned relief dampers 14 to introduce an amount of outside air equivalent to the amount of return air relieved to the atmosphere by the relief dampers 14.

From the outside air intake section C the circulated air passes through the air cooling section D in which the cooling means 24 of the present invention is disposed for cooling and dehumidification of the circulated air as will be described in detail hereinbelow.

The cooled and dehumidied air then passes through the air heating section E where the air is heated to its desired ultimate temperature by a bank of heating coil units 26 disposed fully across the air plenum chamber.

4 These heating coil units 26 are conventional units through which heated Water is circulated by connecting piping 28, with a flow control valve 30 provided in the piping 28 for regulating the temperature of the units and thereby regulating the amount of heating of the circulated air.

Finally, the now completely conditioned air passes through the discharge section F, in which a large capacity fan unit 32 of conventional design is located with its intake 34 in the air plenum chamber for drawing the conditioned air from the chamber and through the discharge port 36 of the fan unit 32 into suitable ductwork leading to the building space being conditioned. It is this fan unit 32 that creates the air circulation through the system and particularly the air fiow through the air plenum chamber in the direction indicated in the accompanying figures.

Referring now in detail to the air cooling section D, the air cooling means 24 of the present invention, which is disposed in this section, includes a vertical series of finned cooling coil units 38 located in the housing 10 and extending the full height of the air plenum chamber, with each unit 38 extending across the full width of the housing 10 except for a small space at one side which accommodates piping and which is closed by Vertical plates 40 to prevent air iiow therethrough. Thus the series of cooling coil units 38 is located across the full path of the circulated air for the passage of the air therethrough to effect cooling and dehumidification thereof.

Each of the cooling coil units 38 is a conventional water-cooled unit having a peripheral frame 42 in which are mounted a plurality of closely spaced, vertically disposed, rectangular, heat-transfer fins 44 having straight outer edges 46 that extend along the faces of the unit. Extending transversely across the unit and through the fins 44 are a plurality of horizontal tubes 48 through which chilled Water is circulated from headers 50 formed in the sides of the frame 42. Chilled water from a conventional source is fed to the upper end of one of the headers 50 through supply piping 52 and returned to the source, after passing through the tubes 48, by return piping 54 connected to the lower end of the header 50, the supply and return piping 52 and 54 lbeing located in the space closed by the aforementioned plates 40. With cooling coil units of this type the circulated air is cooled as the air passes through the units by heat transfer to the fins 44 and tubes 48, which are cooled by the circulating chilled water. The amount of cooling can be regulated by adjustment of the flow rate of the chilled water through the unit, for which purpose a control valve 56 is included in the supply piping S2.

The circulated air is also dehumidified as it passes through the cooling coil units 38 by condensation of moisture from the cooling air onto the fins 44. The condensed moisture ultimately flows into iianged drain pans 58 located immediately below each cooling coil unit 38, from which it drains progressively to lower drain pans and finally to a main drain through vertical drain pipes 60 that are connected to and extend downwardly from the drain pans 58.

In prior art systems handling air flowing in a horizontal direction, cooling coil units of the above described type are normally mounted vertically with the number and size of units dependent upon the air fiow capacity for which the system s designed. In this regard, such vertically disposed units impose a limitation on the air velocity that can be accommodated in the system, beyond which the units fail to cool and dehumidify the air effectively. Thus, large housings must be provided for large capacity systems to maintain sufiicient overall air fioW at the limited velocities.

By the present invention, the cooling coil units 38 are inclined substantially from a vertical disposition, thereby increasing proportionately the effective cooling surface of the units in relation to the cross-sectional size of the air plenum, and increasing substantially the air iiow velocity capacity of the system. As a result, a relatively small size housing and correspondingly reduced size components can be utilized in a relatively large capacity system.

The inclination of these cooling coil units 38 is such that they are sufficiently inclined from a horizontal disposition to cause moisture condensing thereon to begin gravitating along the units to form into drops rather than forming a film that would obstruct air flow, as would be the case were the inclination substantially closer to horizontal. On the other hand, the inclination from horizontal is sufficiently limited to dispose the units at a suficient displacement from a vertical disposition to obtain the aforementioned compactness and high velocity advantages as 'well as to cause the condensate drops to drip from the units before reaching the lower ends of the units for effective condensate discharge.

The inclination of the cooling coil units is in the general range of 25 to 60 from a horizontal disopsition. The particular inclination for optimum results is determined by a consideration of: (a) the ratio of latent heat to sensible iheat, which affects the amount of moisture condensed on and drained from the cooling coil units, (b) the velocity of the air passing through the cooling coil unit in relation to the amount of air bypassing the cooling coil units, (c) the particular fin configuration and the number of fins in the cooling coil units, and (d) the amount of foreign matter expected to accumulate on the fins during use. As a general rule, optimum results are obtained in a usual commercial installation with an inclination of approximately 28 to 30. In the illustrated preferred embodiment the inclination is 28.

In the illustrated embodiment, the cooling coil units 38 are vertically aligned and identically inclined from a horizontal disposition with the lower end 62 of each unit spaced downstream from its upper end 64 to present an upstream face 66 to the horizontal flow of circulated air at the aforementioned inclination. With the units so disposed, the lower end 62 of the upper of adjacent units is spaced downstream from the upper end 64 of the adjacent lower unit and the upper end 64 of the lower of adjacent units extends slightly higher than the lower extent of the lower end 62 of the adjacent upper unit. As a result, the entire vertical cross-sectional area of the combined cooling coil units 38, except for the small area occupied by the upper ends 64 of the units, is utilized for cooling, thereby further contributing to the reduction in the necessary housing size required for a large capacity system.

As the aforementioned upstream faces 66 of the cooling coil units 38 are inclined, they not only face the air ow but also face downwardly substantially so that moisture condensing on the fins 44 and gravitating as drops along the outer edges 46 thereof will drip from the upstream faces 66 along substantially the entire surface thereof rather than running down to the lower ends 62 before dripping off. These condensate drops are collected in drip pans 68 disposed under the upstream faces 66 of the units and extending fully thereunder. All but the bottom one of these drip pans 68 are located between vertically adjacent cooling coil units 38 and extend between the lower end `62 of the upper of adjacent units and the upper end 64 of the lower of adjacent units at a slight sloping toward the drain pans 58, to which they are connected for run-off of collected condensate thereto.

In many conventional air conditioning systems, the sensible cooling and dehumidification produced by cooling coil units are regulated to produce the desired conditioning results by providing a passage through which a selected portion of the air ow is directed for bypassing the cooling coil units. Such bypass passages normally occupy a cross-sectional area within the housing in addition to the area occupied by the cooling coil units so that a larger housing size is required than for a similar system without a bypass passage.

By the present invention, however, bypass passages are uniquely provided without requiring an increase in housing size despite the fact that the housing is no larger than that required for the inclined cooling coil units 38. This results from the combination of the vertical arrangement of the series of cooling coil units 38, the inclination of the units, and the location of the lower ends 62 of upper adjacent units at about the same level as the upper ends 64 of the lower of adjacent units, whereby adjacent units are spaced apart to form bypass passages 70 therebetween while the upstream faces 66 of the units occupy substantially the full vertical cross-sectional area of the housing 10 as described hereinabove.

The location of these bypass passages 70 between cooling coil units 38 permits the use of a simple and inexpensive bafile arrangement for regulating the bypass fiow as the aforementioned drip pans 68 can perform the function of baflies. For this purpose the drip pans 68 are connected to the aforementioned drain pans 58 by hinges 72 secured to the undersides of the upstream ends 74 of the drip pans 68 and to upstanding flanges 7-6 at the upstream edges of the drain pans 58, which locates the downstream ends 74 of the drip pans 68 immediately below the lower ends 62 of the cooling coil units 38 for prevention of substantial air ow between each drip pan 68 and the cooling coil unit 38 thereabove, the spacing therebetween being sufficient only to allow draining of condensed moisture from the drip pans 68 to the drain pans 58.

As aforementioned, the drip pans 68 that are between adjacent cooling coil units 38 extend under the upstream faces 66 of the units thereabove and extend to the upper ends 64 of the units therebelow, on Which upper ends 64 the drip pans 68 are seated to complete the formation of a baffle to restrict air flow through the bypass passages 70 between units when bypassing is not desired.

Air is prevented from passing under the lowermost of the cooling coil units 38 by the location of its lower end 62 closely adjacent the adjacent drain pan 58, which is mounted directly on the bottom of the housing 10, and by the aforementioned drip pan disposition immediately below the lower end 62 of the unit.

To allow a selectively controlled portion of the air ow to bypass the cooling coil units 38, means 78 is provided for moving the drip pans 68 by selectively pivoting them about the hinges 72, thereby moving the dripv pans 68 with respect to the upper ends 64 of the units therebelow to provide an opening therebetween for air ow through the bypass passages 70. This moving means 78 includes a baffle motor 80 of conventional design having a vertical reciprocal piston 82 to which one end of an operating lever 84 is connected. This operating lever 84 is connected intermediate its ends by a pivot pin 86 to a pivot support 88, and at its other end it is slidably connected in a sleeve 90, which is pivotally connected to a ring 92 on a vertical connecting rod 94, with the ring 92 adjustably secured to the connecting rod 94 in proper operating position by a set screw 96. The vertical connecting rod 94 extends adjacent the upstream ends of all of the drip pans 68 and has secured thereto brackets 98 that extend under each of the drip pans 68 for connection through pivot pins to brackets 102 depending from the upstream ends of the drip pans 68. Thus, movement of the piston 82 of the bafile motor 80 is transmitted through the operating lever 84 and the connecting rod 94 into simultaneous pivoted movement of the drip pans 68 to open or close the bypass passages 70, with the slidable connection of the operating lever 84 in the sleeve 90 accommodating the different arcuate movements of the operating lever 84 and the drip pans 68 (the length of the operating lever 84 and sleeve 90 being contracted in FIG. 4 for proper location of the figure on the drawing sheet).

When the bafle motor 80 is inoperative, the drip pans 68 are seated on the upper ends 64 of the cooling coil units 38 therebelow, as shown in solid lines in the figures, thereby closing the bypass passages 70` so that the entire air ow is directed through the units for cooling and dehumidification. To allow a portion of the air ow to bypass the cooling coil units 38 and thereby regulate the sensible cooling and dehumidiiication, the batile motor 80 is energized to extend the piston 82 to some selected intermediate position, thereby raising the drip pans 68 to a selected intermediate position, such as that shown by the lower light lines in FIG. 4, at which the bypass passage 70 is partially open and the upstream faces 66 of the units are partially blocked off. When the baie motor 80 is fully energized, the piston 82 is fully extended, thereby positioning the drip pans 68 against the upstream faces 66 of the units as shown by the upper light lines in FIG. 4, to open the lbypass passages 70 completely and to block off completely the cooling coil units 38 so that they are rendered inoperative.

To effect such complete blocking off of the cooling coil units 38 and to assure collection of condensate drops in all positions of the drip pans 68, all of the drip pans 68 extend suiiiciently upstream with respect to the upstream faces 66 of the units to be moved into fully raised positions in complete covering relation across the upstream faces 66 of the units.

Complete blocking 01T of the cooling coil units 38 is utilized when the weather is cold enough not to require cooling of the conditioned air, which is conditioned only by filtering in the air filter section B, introducing of cold outside air in the outside air intake section C, and heating in the air heating section E during which time the chilled water circulation is not needed and is stopped to avoid the cost of unnecessary continued operation. Because of this complete blocking off of the cooling coil units, the system will function under outside air intake conditions without causing freezing of the water in the cooling coil units at lower outside air temperatures than can be accommodated in prior art systems.

During cold-weather operation of prior art systems it is necessary to drain the water from the units to avoid damage due to freezing of the water. Such draining, however, restricts the versatility of the system when the weather fluctuates frequently between cold and warm as it is then necessary to frequently drain and refill the units to obtain continued utilization of the system.

With the present invention the cooling coil units 38 are protected from temporarily cold conditions so that they can be activated and deactivated rapidly without draining and relling delays. This advantage is obtained by the aforementioned blocking oif of the units, and by including in each drip pan 68 a layer 104 of heat insulating material of any conventional type that prevents substantial heat transfer between the circulated air and the units.

From the foregoing description of this preferred embodiment, it is evident that the present invention provides a simple, inexpensive, eicient and versatile means for cooling air in an air conditioning system, and that a large capacity system can be made highly compact. The advantage of a compact design provides a special advantage in reducing cost of manufacture and installation as the housing and the components contained therein can be preassembled at the manufacturing plant and shipped by conventional carrier in sections to the installation site, where the sections are readily connected to form a completed installation without the problems and expense of assembly from parts at the installation site.

To allow entry of a workman into the housing 10 when desired during installation or when required for maintenance, access doors 104 are formed in one Wall of the housing 10. These access doors 104, shown open for purposes of illustration in FIG. l, as well as the corresponding access space within the housing 10, may be eliminated to allow an even more compact housing design, or may be reduced in size to allow a workman to only partially enter the housing.

The air conditioning system described is controlled by conventional controls to regulate the operation automat- 8 ically to obtain desired results. As such controls and regulation are well known in the art, a detailed description is not inclu-ded herein.

It is to be understood that the present invention is not intended to be limited to the preferred embodiment described herein or to the particular air conditioning system described. For example, the arrangement and number of cooling coil units and bypass passages may be varied, a single cooling coil unit may be used, cooling coil units of other types and coolants other than water may be used, various other mechanisms for moving the drip pans may be used, the drip pans may be mounted for movement other than by pivoting, an additional bypass may be included, and other variation that take advantage of one or more of the features of the present invention may be made. Similarly the other components of the system may be varied in structure or location or may be eliminated, additional components or features may be added, or the system may be designed for air flow in a direction other than horizontal.

I claim:

1. In an air conditioning system having an air plenum chamber in which air is conditioned as it is circulated therethrough in a predetermined direction, means for cooling the circulating air, said means comprising a finned cooling coil unit located in said air plenum chamber in the path of the circulated air for the passage of air therethrough to effect cooling thereof, said cooling coil unit being inclined from a horizontal disposition with its lower end spaced downstream from its upper end, the inclination of said cooling coil unit being suicient to cause moisture condensing from the cooling air onto the cooling coil unit to begin gravitating along the upstream face thereof sufficiently to form into drops that drip therefrom, said inclination being sufficiently limited to disposed said cooling coil unit at a suicient displacement from a vertical Idisposition to cause drops to drip therefrom before reaching the lower end thereof, and a drip pan disposed immediately below said cooling coil unit lower end to prevent substantial air flow therebetween and extending under said upstream face of said cooling coil unit for collection of said drops therefrom.

2. In an air conditioning system, means for cooling circulated air according to claim 1 and characterized further in that said cooling coil unit is arranged for conditioning air that is circulated through said air plenum chamber in a generally horizontal direction, said inclination providing effective cooling of air at a high ow rate.

3. In an air conditioning system, means for cooling circulated air according to claim 2 and characterized further in that said cooling coil unit is disposed at an inclination in the general range of 25 to 60 from a horizontal disposition.

4. In an air conditioning system, means for cooling circulated air according to clairn 2 and characterized further in that said cooling coil unit is disposed at an optimum inclination of approximately 28 to 30 from a horizontal disposition.

5. In an air conditioning system, means for cooling circulated air according to claim 1 and characterized further in that said drip pan is disposed as a baie below said cooling coil unit.

6. In an air conditioning system, means for cooling circulated air according to claim 5 and characterized further by means for moving said drip pan to allow a portion of the circulated air to bypass said cooling coil unit.

7. In an air conditioning system, means for cooling circulated air according to claim 6 and characterized furtheir in that said drip pan is pivoted adjacent said lower end of the cooling coil unit and said drip pan moving means selectively pivots said drip pan to vary the portion of air bypassing said cooling coil unit.

8. In an air conditioning system, means for cooling circulated air according to claim 7 and characterized further in that said drip pan extends sufiiciently with respect to said upstream face of the cooling coil unit to be pivoted into covering relation thereacross to cause said circulated air to bypass said cooling coil unit.

9. In an air conditioning system, means for cooling circulated air according to claim 8 and characterized further in that said drip pan includes a layer of heat insulating material that prevents substantial heat transfer between said circulated air and said cooling coil unit when said drip pan is in covering relation thereacross.

10. In an air conditioning system having an air plenum chamber in which air is conditioned as it is circulated therethrough in a predetermined direction, means for cooling the circulating air, said means comprising a generally vertically disposed series of inned cooling coil units located across said air plenum chamber, each of said cooling coil units being disposed in the path of a portion of the circulated air for passage of air therethrough to effect cooling thereof and being inclined from a horizontal disposition with its lower end spaced downstream from its upper end, the lower end of the upper of adjacent cooling coil units being spaced downstream from the upper end of the adjacent lower cooling coil unit, and a drip pan disposed under the upstream face of each of said cooling coil units for collection of said drops therefrom, the drip pans between adjacent cooling coil units extending between the lower end of the upper of said adjacent -cooling coil units and the upper end of the lower of said adjacent cooling coil units to provide a bafe that restricts air flow therebetween.

11. In an air conditioning system, means for cooling circulated air according to claim 10 and characterized further in that the inclination of said cooling coil units is sufficient to cause moisture condensing from the cooling air onto the cooling coil units to begin gravitation along the upstream faces thereof sufficiently to form into drops that drip therefrom, and said inclination is sufticiently limited t0 dispose said cooling coil units at a sufficient displacement from a vertical disposition to cause said drops to drip therefrom before reaching the lower end thereof.

12. In an air conditioning system, means for cooling circulated air according to claim 11 and characterized further in that said cooling coil units are disposed at an inclination in the general range of 25 to 60 from a horizontal disposition,

13. In an air conditioning system, means for cooling circulated air according to claim 11 and characterized further in that said cooling coil units are disposed at an optimum inclination of approximately 28 to 30 from a horizontal disposition.

14. In an air conditioning system, means for cooling circulated air according to claim 10 and characterized further by means for moving the drip pans between adjacent cooling coil units to allow a portion of the circulated air to bypass the cooling coil units.

15. In an air conditioning system, means for cooling circulated air according to claim 14 and characterized further in that the drip pans between adjacent cooling coil units are pivoted adjacent the lower ends of the upper of the adjacent cooling coil units, and said drip pan moving means selectively pivots said drip pans to -vary the portion of air bypassing said cooling coil units.

16. In an air conditioning system, means for cooling circulated air according to claim 10 and characterized further by means for moving said drip pans to allow a portion of the circulated air to bypass said cooling coil units, and in that said drip pans extend sufficiently with respect to said upstream face of the cooling coil units to be moved selectively by said drip pan moving means into covering relation thereacross to cause substantially all of said circulated air to ybypass said cooling coil units.

17. In an air conditioning system, means for cooling circulated air according to claim 16 and characterized further in that each of said drip pans includes a layer of heat insulating material that prevents substantial heat transfer between said circulated air and said cooling coil units when said drip pans are in covering relation thereacross.

References Cited UNITED STATES PATENTS 2,744,393 5/1956 Brugler 62-285 2,817,959 12/ 1957 Lustwerk 62-314 3,299,660 1/ 1967 Sullivan 62-285 3,303,666 2/ 1967 Toper 62-285 WILLIAM I. WYE, Primary Examiner U.S. C1. X.R. 

